Sunscreens: Shielding our skin from harmful sunrays
As the summer season is at its peak with temperature rising high even above 50ºC and sun rays literally imparting sun burn feeling as we move out even during the morning hours while going to work or some other day-to-day activity, thus everybody looks for safe options to protect ourselves from this prickling heat and sun burn. We try wearing light colored cotton clothes, carry umbrellas, put on sunglasses and sunhats etc. Another preferred sun protecting product is sunscreen that works as sun block and its topical application over skin prevents sun burn and related skin diseases. Due to availability and marketing of a variety of sunscreen products, there is a remarkable increase in their purchase and use in India as well as globally, particularly in urban regions.
Why at all sunscreens are required and how they really work?
The broad spectrum of UV radiation (40–400nm) has two components among others which penetrates the Earth’s surface and are responsible for sunburn or related effects- UVA: 320–400nm and UVB: 290–320nm. Long term exposure to UVA even at low dose causes skin tanning, pigmentation, reduction in skin elasticity, premature aging, melanocytes mutation, immune suppression, and skin cancer. While UVB is primarily responsible for sunburn (acute damage), immune suppression, and skin cancer (chronic damage). The increasing incidence of sunburn and related skin effects/diseases due to UV radiation and its awareness has led to an increased usage of sunscreen products. The chemicals used in sunscreen i.e., UV filters protect skin by scattering or reflecting solar radiation. The commonly used inorganic UV filters like zinc oxide, titanium oxide acts as a thin protecting layer over skin upon topical application, thereby scattering and reflecting UV light as skin is exposed to Sun. Other category is organic UV filters like benzophenones, salicylates that absorbs UV light through their chemical bonds and releases heat upon their break down. Overall, the efficacy and safety of these sunscreens is of high concern.
How is the efficacy of sunscreens measured?
There are relevant testing standards set by International Organization for Standardization (ISO) which are used for measuring sunscreens efficacy. The major parameter used for efficacy determination of sunscreen is Sun Protection Factor (SPF) which determines that upon sun exposure to the skin how efficiently sunscreen absorbs or reflects UV radiation mainly UVB. It is calculated as the ratio of radiation required to burn the protected skin to the radiation required to burn the same skin without sunscreen, considering all other factors as constant. That means higher the SPF number, higher will be the protection of skin from sun. The SPF number ranges from 2–60, however higher SPF usually above 50 provides very small additional protection. Also, though SPF number is high but the amount applied is usually low and reduce in cream on skin happens due to friction with clothes, sweating etc. Another factor is for UVA i.e., UVA protection factor (UVA-PF) which is determined by measuring in vitro UVA transmittance by sunscreen, a value that reflects in-vivo protection conferred by that sunscreen upon application. Furthermore, water resistance of sunscreen is another important factor as high perspiration or sweating during summers might easily wash off applied sunscreen.
Is sunscreen a cosmetic product or medicated product or another category?
Under the umbrella of risk assessment and management, expert working groups and regulatory agencies implements different norms and regulations in each region for environmental and human health safety. Sunscreen creams are categorized differently across the globe and regulated under respective legislator norms to ensure availability of safe and effective sun protection products to the consumers.
In European Union (EU) and United Kingdom (UK), sunscreens are considered as cosmetics or personal care products and follows cosmetics product regulation norms providing recommendation on efficacy and sun protection claims. Updated guidance document indicated efficacy of sunscreens should be for both UVA and UVB and further detailed the labelling instructions which should be clearly mentioned on the product to help consumers buy that product knowing its claims, potential dangers, and safety tips for usage.
In India also sunscreens are considered as cosmetics and Bureau of Indian Standards (BIS) has listed standards for testing sunscreen skin care leave on products and has also provided list of permitted UV filters which these sunscreen products may contain. However, there is no recommended maximum permissible SPF rating yet.
In USA, sunscreens fall under over-the-counter drugs category, regulated by US Food and Drug Administration (FDA). New rules were implemented providing list of active ingredients under “generally recognized as safe and effective (GRASE)” category pertaining to safety issues. Besides, recommendations were proposed for broad spectrum efficacy of sunscreen, water resistance, labelling to provide key information to consumers and testing requirements.
On similar lines, sunscreens are regulated in different regions across the globe either as cosmetics, special use cosmetics (China), OTC drugs (Canada), therapeutic goods (Australia), or quasi drugs (Japan) and provides recommendations regarding efficacy, testing mandates, active ingredients/UV filters, permissible SPF value and labelling requirements. The guidance documents are updated on regular basis as per the latest evidence analysis considering safety issues.
A lot of confusion among consumers!
Many of us are very confused when it comes to choosing a sunscreen amongst array of choices available! Further concerns are regarding its application, usage, and stability under prolonged exposure to sun rays.
An ideal sunscreen should be non-irritating, nontoxic, safe, and able to completely protect our skin from sunrays. It should effectively block both UVA and UVB rays. Environmental working group (EWG) provides a database and a guide to sunscreens that provides information regarding efficacy of each product that is the key information a consumer looks for while purchasing. Further, it provides list of products suitable for babies and kids, although not toxic but it is recommended not to use sunscreen for babies till 6months-1year. Regardless of age, geographical location, gender, sunscreen can be effectively used to protect skin from harmful sun rays. While purchasing, the labelling information should be carefully read and understood by consumer for usage, warning signs, skin sensitivity and safety tips and should be carefully checked for any allergic response before application. Once tested, before going out, following manufacturer’s instructions sunscreen should be uniformly applied on sun exposed areas and should be reapplied after vigorous activity or excessive perspiration.
Mind it! Using sunscreen does not mean you can stay longer in the sun; it is just one of the measures to protect yourself from Sun when you cannot skip going out under the Sun.
Research to risk management: Skin microbiome and next generation sunscreens
A lot of technical and toxicological challenges are there when it comes to formulating sunscreens. The product should be effective and safe for human health as well as environment as it washes off from the skin. The product needs to be formulated such that it is cosmetically accepted, should not penetrate beneath the upper layer of skin, and efficiently prevents skin from damage. Recently, another concern or cumulative impact of sunscreens usage is reported on human skin microbiome. The huge number of microorganisms that our skin hosts together comprise skin microbiome and very much influences health or disease condition and vice-versa. The UV filters used in sunscreens were reported to have bactericidal effects and many chemicals used in sunscreen production may negatively impact cutaneous microbes. Though a healthy skin microbiome and microbial compounds were reported to protect skin from UV radiations, some of the traditional sunscreens have the capacity to reduce beneficial microbial diversity of skin. Thus, extensive studies are required to design and formulate next generation sunscreen products which not only prevents skin from sun rays but also preserves the skin microbiome with minimal effect on microbiota or work commensally with skin microbiota.
